利用偏振成像检测植物叶片含水量早期变化  

Early change detection of plant leaf water content using polarization imaging

作　　者：徐翔 刘增辉 陈志坚 姬业钦 石雨萍 狄慧鸽[1] 汪丽[1] 华灯鑫[1] XU Xiang;LIU Zenghui;CHEN Zhijian;JI Yeqin;SHI Yuping;DI Huige;WANG Li;HUA Dengxin(School of Mechanical and Precision Instrument Engineering,Xi'an University of Technology,Xi'an,710048,China)

机构地区：[1]西安理工大学机械与精密仪器工程学院,西安710048

出　　处：《农业工程学报》2023年第11期175-182,共8页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金青年项目(62105259);2022年陕西林业科技创新专项(SXLK2022-02-6)。

摘　　要：为了实现含水量早期变化的精准识别并进行迅速干预,减少植物缺水带来的损失,该研究基于双波片旋转法搭建了一套偏振光成像系统,通过对冬青叶片Mueller矩阵图像及退偏指数图像的分析与试验。实现了对冬青叶片含水量的早期检测。结果表明:首先,退偏指数图像可以清晰地反映冬青叶片含水量的变化,经分析发现随着冬青叶片含水量的逐渐降低,叶肉组织上的退偏指数在不断增大;其次,进一步建立了冬青叶片的含水量预测模型,得到退偏指数与含水量的拟合曲线,拟合曲线的决定系数值为0.95。随后,选用不同部位的冬青叶片对预测模型进行验证,含水量预测值与实际值间的最大相对误差为4.90%,即只需对叶片退偏指数进行探测即可获取到该叶片当前的含水量状态。该研究为植物含水量变化的早期识别提供了新方向,同时也为植物盐、酸和肥胁迫等生理状态的快速无损检测提供了理论基础。Water content is crucial to plant growth.Water shortage can cause a decrease in photosynthesis and respiration efficiency during growth,directly leading to the yield of plants and crops.An accurate identification can greatly contribute to the water change of plant leaves in the early stage of water shortage and intervene rapidly.It can greatly reduce the loss of plants and crops due to water shortage.However,there is little change in the water content and no outstanding change in the plant morphology and spectral characteristics during the early stage.It is a high demand for the early identification of plant water content change at present.Two measurements can be widely used in the plant water content.One is the direct measurement(such as drying,and distillation),where the measurement accuracy is higher,generally as the standard of other methods.Another is the indirect measurement using,such as the plant stem diameter,canopy temperature,conductivity,microwave,spectroscopy,and images.In this study,a set of polarized light imaging systems was built to add the light source,and polarizer in the image detection.The polarized light imaging detection was then carried out on the holly leaves with different water content.The polarization of light that carried the multidimensional vector information was used as the information carrier to transmit more abundant information.The multi-dimensional vector that carried in the light polarization information was used to detect the different water content of holly leaves,in order to realize the early identification of water content change.The main conclusions of this study were as follows.1) The m13 and m^(3)2 matrix elements in the Mueller matrix image initially reflected the change of water content of holly leaves,but there was no outstanding difference in the early stage of water content change.2) The depolarization index image clearly showed the change in the water content of holly leaves at each stage.Specifically,the depolarization index increased with the continuous decrease

关 键 词：含水量 无损检测 叶片 偏振探测 退偏指数 MUELLER矩阵 

分 类 号：S24[农业科学—农业电气化与自动化] S123[农业科学—农业工程]